Date: Sun, 04 Mar 2007 20:52:45 GMT From: - Bob - <uctraingnospamanet.com> Subject: Re: '99 9-5 hooter valve options?
On Sun, 04 Mar 2007 10:05:13 GMT, johannes <johsnospamnospamfitter.net> wrote: >The function of the bypass valve is to keep the turbo spinning when going >off the pedal, thereby reducing turbo lag. I don't see how that can >increase HP. Strictly speaking, the hooter valve is used to vent excess pressure when you close the throttle plate. Otherwise the intake system would likely blow something off. An alternative would be to open the wastegate and allow the exhaust flow to bypass the turbo. I don't know if that is not done because of the reason you stated above (keep the turbo spinning) or because you can't vent pressure fast enough through the relatively slow wastegate operation (vs. the fast acting hooter valve). Perhaps it's a combination of the two.
